The objective of this project is to identify a common genetic defect in the African population that may have important public health implications both in Africa and the United States and to obtain a greater understanding of the mechanism of iron metabolism. The specific aims of the proposed research project are: 1) To characterize the iron status and obtain DNA samples and immortalized cell lines from members of African families identified by index subjects with iron overload; 2) To determine the chromosomal localization of the iron loading locus in these families by employing DNA microsatellite mapping techniques and the previously developed likelihood analysis of iron status; and, 3) To examine loci for proteins important in membrane transport of iron and in regulation of intracellular iron metabolism as candidate genes for the genetic defect in African iron overload. These objectives will be obtained through the services of the Contractor in the collection of blood samples and the recordation of newly established pedigrees as identified from index cases of iron overload. The Contractor will perform clinical laboratory assays on the blood samples and will also send the samples to the laboratories at the NICHD for the molecular studies.